Mille og hendes mor åbner i 1950'ernes Danmark en milkshakebar, hvor de unge kan hænge ud og lytte til jukeboksen. Men Mille drømmer mest om at blive skuespiller og sanger og stå overfor filmstjernen Johnny Rocket. Imens skaber Johnny Rocket problemer for filmstudiet Movie Star ved kun at ville spille overfor den kvinde han elsker. Det giver problemer for producenten Volle, der er ved at sætte en Askepot-musical op med Johnny i hovedrollen.

Set in the rock'n roll universe of the 1950s, »Cinder Rock'n Rella« is a classic tale, about Mille, who lives with her mum and dreams of becoming a musical star. When they stake all they have on a new milk-shake bar things begin to look up and the local film studios even want a girl to play a leading part that's just up Mille's street. But mum suddenly dies, leaving Mille deep in debt to her evil auntie and cousin, who'd rather be rid of Mille once and for all. Luckily heaven sends a couple of angels and Topper, a good fairy.